The present invention relates to a core sampling device, in particular a drill bit and core barrel assembly for a wire-line drilling method of obtaining core samples.
In a commonly known wire-line core sampling device, the drill bit comprises effectively an annular cutting device which cuts an annular or cylindrical hole. This hole defines a core which is captured within a core barrel for sampling.
Devices of this kind suffer the disadvantage that it is not possible to change the drill bit e.g. to accommodate changes in geological conditions or simply to replace a worn bit, without withdrawing the entire drill line.